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About JFRM250

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  1. So are you saying all this re: drilling holes in piston (wth?) applies not only to 125's but to 250's and 80's as well? There seems to be a lot of debate on this and in the end I thought it was only the pre-2001 model years---and I'm only speaking to 250's for SURE here, your 125's aside---that required the $30 plug because of the underlying issue.
  2. Yeah but those $30 expensive plugs were only for the late 90s through 2000 model years I believe. The 2001 and beyond uses a more basic NGK plug or you can spend a few bucks more and go with iridium. This is specified in the service manual for my 2001 and also in the Clymer guide I bought for the rebuild (which by the way is an excellent guide in my humble opinion). Rebuilding the top end is easy as I came to learn. The bottom end is somewhat of a bitch by comparison, but certainly doable by a novice such as myself (accompanied by a good manual/guide!) For the bottom end, you just need the right/specialty tools to split the case properly and pull the crank, bearings and seals and what-not. Yes, when you rebuild the top end you’re basically looking at a cylinder replate (if inspection shows significant scarring/scuffing/wear), a new piston and rings of course, and conrod pin. You should also inspect the underside of your cylinder head for evidence of detonation and damage in general. You’ll also need a set of new gaskets for the head to cylinder, and bottom of cylinder to bottom end. Don’t even think of reusing the old ones. [emoji1360]
  3. I have a 2001 RM250 that I rebuilt top & bottom end on last winter. Didn't know there's a 'special plug' for the 01 125, but there isn't one for the 01 250 at least. Anyhoo... For your top end rebuild I'd get that cylinder replaced for sure given the look of it. How's the head itself look? Millenium did my replate and they do a great job overall, come highly recommended, etc. If you go with them send them your new piston as well for sizing purposes during replate work. They'll explain to you if/when you contact them --- I talked to a guy named Rod Heaton (rheaton@mt-llc.com) who was very helpful/responsive etc. I couldn't be more please with the work they did on my cylinder. I also sent them the crank itself along with conrod. They did a rebuild of the crank and welding for new conrod/big pin but I only did all that because the seals and bearings in mine were questionable and I figured 'while I'm at it' and had the bottom end pulled apart I might as well do a complete rebuild down there as well and glad I did because, well, now I know that engine top/bottom. Good luck! But yeah---start with a replate, new piston/rings. Should be good to rip after that!
  4. Or a Holley 4 barrel, lol. Point taken.
  5. Thank you for the offer and I will give this approach an effort as time permits. Will be in touch in this thread. Thanks again!
  6. Here’s the quick and largely unhelpful response I received from JD jetting when I explained everything to them in an email. I think I might have to pick up the phone for this one: “that carb fits you just have to squeeze it in . there is no difference in performance.” (Nice, huh?)
  7. I recently ordered a JD Jetting JDKHO8: https://jdjetting.com/product/jdkh08-keihin-38mm-pwk-airstryker-w-jet-kit/ My existing carb is giving me fits (let's not get into the why's and all that). Trust me, I've done just about all I can with the existing stock carb following a complete top/bottom end rebuild. Anyway, the JDKH08 is what JD Jetting said would work for my 2001 RM250 (as did Motosport, which agreed that this would be a replacement that would work/fit fine). It does not. First, the top of the JDKH08 is 'round' whereas mine is more than oval/football shape with 2 allen screws in the top. Second, the top to bottom dimension is the same at about 6" but the front to back (intake to boot) is a full half inch shorter (at 3 inches) on my existing PWK38PWJ/TPS than it is on the Airstriker JDKH08. JD Jetting (and as it goes, Motosport) offers an 'AG' model which perhaps is what I'm looking for? I've sent this inquiry to JD Jetting as well. Maybe you guys think that, despite the front/back measurement making thing notable TIGHTER in there, and despite the top round vs oval factor, I could still make a JDKH08 work somehow? If so, how? The Airstriker is supposed to be a VERY decent replacement for the stock carb.
  8. I get that EXACT same intermittent surge when idling / low rpm's. Anyone still following this now 9 yr old thread? 48 pilot, 158 main, 40:1. Rebuilt carb as well. Complete top and bottom end rebuild this past winter, about 10 hours on the rebuild. Runs great otherwise. Can be fickle/tricky to get started once warmed.
  9. Words of wisdom. Likely done 'for a reason' and while helicoil has its place, you might consider the age of the bike and why PO epoxied it to begin with. If a tap-tap-tap chisel approach ends up with a broken piece of the boss then you'd likely find yourself in (screwed) position of trying to find another case half (harder with bike's age) and in the process be forced to do a bottom end rebuild (not the worst thing in the world, but hardly trivial work, lost riding time in mid-season unless year round where rider lives, etc).
  10. If you’re going to chisel it off and Helicoil it or whatever, be careful that you don’t break off part of the boss itself in which case you’ll be pretty screwed and may be looking at a new case cover. If it doesn’t leak, you should probably leave it as is, and as already suggested just take off the clutch cover and tip the bike over on its side to empty the oil.
  11. That’s a very valid point. When were the cases last split and seals/bearings inspected? Top end and cylinder rebuilds/refurbs are cake, but bottom end work is probably more often than not neglected I bet (due to comparably higher effort vs top end stuff).
  12. My '01 RM250 was running rich, and I do similar riding to yours. Plug would get oil/wet/black but not necessarily fouled. So I tried a few things here and there based on suggestions in here. Specs currently are: FMF Gnarly with (just packed) TurbineCore 2, following full top/bottom end rebuild over winter including all seals, bearings, gaskets, o-rings, conrod, piston, rings, replated cylinder. Stock PWK38 'rebuilt' with ProX kit Just replaced the jet block o-ring (was somewhat frayed, suggested by others/vendors too for aiding in what would be difficult starting at times) New Boyesen Power Reeds (in stock cage) Float level APPEARS to be within the .26" spec. (I've looked at it / tilted / measured it more times than I care to admit) 45 OEM pilot (down from 48), 162 main (from kit), needle clip at top/leanest position (moved from 2nd). Needle is stock for an '01 250 --- I forget the 'code'. Air screw 1.75 turns out. Color/condition of plug is now MUCH better. Bit of spooge out of tail, but not bad. Running 93 oct 10% ethanol gas (can't find the pure stuff around here) with 40:1 ratio using Bel Rey MC1 (low flash point, which is fine for slower woods/trail riding). I STILL think I have a bit of jetting to do, but I'm getting close. Dialing in the jetting can be a pain (quite an art) but it's been satisfying getting it closer to ideal. Hope this helps.
  13. I ride (in Missouri) at: St Joe’s, Ride Organic, and Finger Lakes. Mostly trails m’self. Too much of a fogey to do motoX.
  14. The throttle slide itself is not damaged. What you may be referring to is my first post of this thread where I said there was a small chunk/corner of the jet block itself that had broken off, but the consensus seems to be that it doesn't affect/impact fuel delivery in any way. I also reamed out that corroded (exterior) 'starter jet' so that's all cleaned out/confirmed. Didn't notice it being difficult to ream or sense that it was blocked or anything. The spec for float height of that particular carb (PWK38) is .26" It's just that I'm eyeballing best I can, with a tape measure, while tilted, such that I measure only when the float valve is just barely having the float tab touching it (before it compresses). It's pretty darned close to that quarter inch---or so I like to think.
  15. Thanks. Re: slosh theory, would that come back to adjusting/checking the float level by tilting the carb as the manual/Clymer suggest and measuring it to the .26" high spec? I find that to be somewhat tricky and have 'to the best of my ability' attempted more than a couple times to 'set it' to that spec/range, but is it exactly to spec? I'm just not sure. Also, would it really 'slosh' around the float bowl after I've been at a standstill for a good 10 seconds? Sure wouldn't think so? I went from a 48 to a 45 on the pilot and it seems to start somewhat better, so not sure I want to go 'back' to the 48. It did this rev 'blip' thing with the 48 in there as well. Maybe I should go back to 2nd leanest position on the needle jet (bit richer) vs going to the top/first which I'm at now. But first---I'll try the easier route of 1/2 turn in on the air screw and see what that yields. I agree that the color is much more ideal vs fouled/black which it was doing originally before I started monkeying with the jetting. Here's a couple short clips with examples of the 'blip rev' in fuel delivery at/near idle, just so you can see it 'in action'.
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